Reassembly free deep packet inspection for peer to peer networks

ABSTRACT

The present disclosure relates to a system, a method, and a non-transitory computer readable storage medium for deep packet inspection scanning at an application layer of a computer. A method of the presently claimed invention may scan pieces of data received out of order without reassembly at an application layer from a first input state generating one or more output states for each piece of data. The method may then identify that the first input state includes one or more characters that are associated with malicious content. The method may then identify that the data set may include malicious content when the first input state combined with one or more output states matches a known piece of malicious content.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention is generally directed to reassembly free scanningof files in a peer to peer network. More specifically, the presentinvention scans file data without reassembling a file even when parts ofthe file are received out of order.

Description of the Related Art

Data communicated over computer networks today pass through variouslayers in a computer system architecture. Typically data is received ata network interface of a computer at a link layer. The link layer is alayer in the architecture of a computer that includes physical hardware.The link layer connects the computer to other computers in a computernetwork. Link layers also are used to transmit data from one computer toanother over a computer network.

Other layers above the link layer in computer system architecturescommonly include a network layer, a transport layer, and an applicationlayer. The network layer receives data packets from and provides datapackets to the link layer. The network layer may also receive data insegments from the transport layer and send data in segments to thetransport layer. Commonly when the network layer receives a segment ofdata from the transport layer it will generate a packet or an internetprotocol (IP) datagram for transmission to another computer. Thisprocess may include encapsulating the segmented data received from thetransport layer and adding a header that includes a destination IPaddress when generating an IP packet. In certain instances more than oneIP packet may be associated with a data segment. The network layer mayalso receive IP packets from the link layer and may pass segmented datato the transport layer.

When a series of IP packets are used to transport data to a computer,those packets may be received out of order at the network layer. Whenthis occurs, the transport layer may re-order the data segments from aplurality of packets before sending the re-ordered data to theapplication layer. Conventionally data received at an application layermust be received in-order (i.e. sequentially). For example, in aclient-server environment file data received at the application layer ofa client or a server must be in-order before it can be processed. Thisis because the client-server environment expects received data to be inorder. While communication transferred over a computer network accordingto the Transmission Control Protocol (TCP) will re-order packets,communications over other transport layer protocols, such as the UserDatagram Protocol (UDP) do not.

Typically in a client-server environment a server will send a data setor a file sequentially from the application layer to the transportlayer, the transport layer may then send that data to the network layer.The network layer then packetizes the data and sends a plurality ofpackets to a client. Even though the packetized data may be sent out oforder, data contained in the packets will be re-ordered before that datais received at the application layer at the client. Because of this,application layers at a client or a server in a client-serverenvironment may never receive file data that is out of order.

Peer to peer (P2P) networks, however, do not operate in the same way asa client-server environment. For example P2P networks may receive dataat an application layer that is out of order. This is because P2Pnetworks fundamentally have a different type of architecture as comparedto a client-server environment.

In a P2P network a computer accessing file data may receive parts ofdata from a file from a plurality of computers. A P2P network is capableof transmitting file data in pieces where each piece of data may betransmitted from a different computer. Because of this a first piece ofdata received from a first computer may be out of order as compared to asecond piece of data received from a second computer. When this occursthe network layer and the transport layer at a receiving computer willnot be aware that the first data piece and the second data piece havebeen received out of order. This is true even when packetized data sentfrom the first computer (or the second computer) to the receivingcomputer have been re-ordered. This is because the network layer and thetransport layer at the receiving computer do not check whetherapplication data received from different peer computers are received inorder. Conventionally, the network layer and the transport layer areonly capable of re-ordering packetized data that has been transmittedfrom a single source computer to a destination computer.

P2P networks may also break a file into a number of pieces where eachpiece may include a pre-determined or specific number of blocks.Information relating to a number of pieces that a data file is brokeninto may be included in metadata (or a metadata file) that is associatedwith the data file. Once a number of pieces are identified, a file sizedivided by the number of pieces will correspond to a number of blocksthat the file may be broken into in the P2P network.

Limitations included in the network layers and in the transport layersof computers today mean that file data received at an application layerof a computer cannot easily scan the received data for malicious content(such as computer worms, viruses, or other attacking software).Conventionally the scanning of data for malicious content at theapplication layer in a P2P network either cannot be done reliably ormust be done in an inefficient manner. For example, if data from a fileis scanned out of order, the scan can miss a virus contained within thedata, because malicious content are characterized by a sequentialordered series of characters, not an out of order series of characters.In another example, when the application layer re-orders received databefore scanning it, data from the out of order pieces must be storeduntil the data pieces can be re-ordered and scanned. Thus, the firstexample is unreliable and the second example is inefficient.

Application data that includes interleaved out of order data received atan application layer of a computer system if scanned in the orderreceived may result in missing malicious content contained within thereceived interleaved data. Furthermore, data received out of order mayalso result in scanning software falsely detecting malicious content.For example, when the character sequence of “car” is associated a virusand two pieces of data that were received out of order where a laterpiece of data ending with the character “c” is scanned before an earlierpiece of data that begins with “ar,” malicious scanning software willfalsely identify that these pieces of data include the virus, when theydo not.

What is needed to increase the reliability and efficiency of P2Pnetworks are systems and methods that scan pieces of data received outof order at an application layer without storing and re-ordering datapieces that have been received out of order. What is also needed aresystems and methods that scan interleaved data reliably at anapplication layer. The reliable scanning of received data at anapplication level increases the reliability of detecting maliciouscontent while reducing the likelihood that malicious content scanningsoftware will falsely associate received data with malicious content.

SUMMARY OF THE PRESENTLY CLAIMED INVENTION

The presently claimed invention relates to an apparatus, a method, and anon-transitory computer readable storage medium for deep packetinspection scanning at an application layer of a computer. A method ofthe presently claimed invention may receive a portion of data at anapplication layer of a computer system after which the received portionof data may be scanned from a first input state at the applicationlayer. When the first input state includes a portion of informationknown to be included in malicious content, the method then identifiesthat the data set can include malicious content after the receivedportion of data has been scanned from the first input state.

The presently claimed invention may also be implemented as anon-transitory computer readable storage medium where a processorexecuting instructions out of a memory receives a portion of data at anapplication layer of a computer system after which the received portionof data may be scanned from a first input state at the applicationlayer. When the first input state includes a portion of informationknown to be included in malicious content, the processor executinginstructions out of the memory then identifies that the data set caninclude malicious content after the received portion of data has beenscanned from the first input state.

An apparatus of the presently claimed invention may include a networkinterface that receives information, a memory, and a processor. Theprocessor executing instructions out of the memory then receives aportion of a data set at an application layer. The received portion ofdata is then scanned at the application layer from a first input state.When the first input state includes a portion of information known to beincluded in a piece of malicious content, the processor executinginstructions out of the memory then identifies that the data set caninclude malicious content after the received portion of data has beenscanned from the first input state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates computers in a client server environment andcomputers in a peer to peer network (P2P).

FIG. 2A illustrates an exemplary way in which data parts from a data setmay be separated into a plurality of data blocks by computers in a P2Pnetwork.

FIG. 2B illustrates data blocks of a data set that are received out oforder at a peer computer.

FIG. 3 illustrates an exemplary sequence that data blocks that werereceived out of order at an application layer may be scanned formalicious content without re-ordering and reassembling those datablocks.

FIG. 4 illustrates a state mapping that includes malicious content.

FIG. 5 is a block diagram of a device for implementing the presenttechnology.

DETAILED DESCRIPTION

The present disclosure relates to an apparatus, a method, and anon-transitory computer readable storage medium for deep packetinspection scanning at an application layer of a computer. A method ofthe presently claimed invention may scan data received at an applicationlayer from a first input state. The first input state includinginformation, such as, one or more characters that can be associated withmalicious content. The method may then identify that the data set mayinclude malicious content when the first input state combined with thescan of the received data matches a known piece of malicious content.

FIG. 1 illustrates computers in a client server environment andcomputers in a peer to peer network. Client computers C1, C2, C3, C4,and C5 each may communicate with server 120 as indicated by the darklines connecting each of the client computers with the server 120 in theclient server environment 110 of FIG. 1. Line 130 illustrates the serversending data to client computer C1. In client server environment serverssend application data directly from the server to a client computer inorder.

The peer to peer (P2P) network illustrated 150 in FIG. 1 includes aplurality of peer computers P1, P2, P3, P4, and P5 that may send datadirectly to each other as illustrated by the dark lines connecting eachpeer computer with each other peer computer. The dashed lines 160, 170,and 180 illustrate peer computers P2, P4, and P5 sending data to peercomputer P1. In a peer to peer computing environment data sent from anumber of peer computers to a particular peer computer may be datablocks from a data set or file that the particular peer computer P1wishes to receive and those data blocks may be received at anapplication layer on peer computer P1 in an out of order sequence.

FIG. 2A illustrates an exemplary way in which data parts from a data setmay be separated into a plurality of data blocks by computers in a P2Pnetwork. A first piece of data Piece 1 from a data set is separated intoa first data block B 1-1 and a second data block B 1-2. FIG. 2A alsoshows a second piece of data Piece 2 from the data set being separatedinto a first data block B 2-1 and a second data block B 2-2. In a P2Pnetwork each of these data blocks may reside at any peer computer in theP2P network. In certain instances one or more data blocks of a data setmay be sent to a requesting peer computer from a second peer computer,and other data blocks from the data set may be sent to the requestingpeer computer from one or more other peer computers.

FIG. 2B illustrates data blocks of a data set that are received out oforder at a peer computer. Note that time in FIG. 2B moves forward fromleft to right along the “TIME” line in FIG. 2B. The ordering of receiveddata blocks of FIG. 2B are: B 2-2, B 1-2, B 2-1, and B 1-1, where the insequence order of these data blocks are B 1-1, B 1-2, B 2-1, and B 2-2.

FIG. 3 illustrates an exemplary sequence that data blocks that werereceived out of order at an application layer may be scanned formalicious content without re-ordering and reassembling those datablocks. Here again the data blocks are received in the out of ordersequence of B 2-2, B 1-2, B 2-1, and B 1-1. Each of the received datablocks are scanned in a manner where each data block scanned hasidentified input states and output states. The identified input statesmay include a state for each and every possible state that might beassociated with malicious content. Identified input states include oneor more characters in a sequence of characters that match content knownto be associated with malicious content.

For example, when malicious content is identified as receiving thecharacter “c” followed by character “a” that is, in turn, followed bycharacter “r,” then the identified input states associated withmalicious content include state “c” and the state “ca.” In the instancewhere a preceding data block ends with characters “ca” and a followingdata block begins with the character “r,” then malicious code “car” ispresent in these data blocks. Similarly in the instance where thepreceding data block ends with the character “c” and the following datablock begins with characters “ar,” then the malicious code “car” is alsopresent in these data blocks. Malicious content “car” may correspond toa rule that identifies “car” as being malicious content.

In the instance where characters “car” are associated with maliciouscode by a rule when data block B 2-2 is received and when data block B2-1 has not yet been received (as in FIG. 3.). Identified input statesan empty string, “c,” and “ca” will then be used when identifyingwhether data blocks B 2-2 and B 2-1 can include the malicious code“car.”

In an apparatus consistent with the presently disclosed invention,malicious code can be associated with one or more different sequences ofcharacters. For example, the character sequence of “Apple” may also beassociated with malicious content via a rule (R2) that identifies“Apple” as being a virus. In the instance when “Apple” is associatedwith malicious content, identified input states (sub-states) may includean empty string “ ”, “A,” “Ap,” “App,” and “Appl.”.

After data block B 2-2 is scanned using each of the identified inputstates in FIG. 3, the scanning process outputs output states 2-2. Outputstates 2-2 may then be stored in memory for later use. Since the nextdata block received in FIG. 3 is B 1-2 and since data block B 1-1 hasnot yet been scanned, the scanning process once again inputs theidentified input states when scanning data block B 1-2, and the scanningprocess outputs output states 1-2. Output states 1-2 may then be storedin memory for later use. FIG. 3 then shows data block B 2-1 beingreceived. Note that data block B 1-2 in FIG. 3 has already been scannedand that output states 1-2 may be input into the scanning process ofdata block B 2-1 from the memory. This is because these two data blocksinclude contiguous (ordered) data and because output states 1-2 werepreviously stored in memory. The outputs of the scanning process of datablock B 2-1 are output states 2-1. The dotted line 310 in FIG. 3indicates that the output states 2-1 may be compared with the identifiedinput states. Any output state 2-1 that matches an identified inputstate may then be used to identify whether the combined data blocks 1-2and 2-1 include malicious content. The process of storing output statesof a scanned data block and correlating those output states toidentified input states that may be included in a subsequently received,previously ordered data piece reduces an amount of memory required toidentify malicious content in a data set. This is because once an outputstate from a second piece of data has been identified, a number ofidentified input states relating to a not yet received first piece ofdata may be reduced. For example, the second piece of data has theoutput state “ca,” the identified input states that can includemalicious content of “car” are limited to one possible identified inputstate of “r.” In such instances identified input states including “c,”“a,” “A,” “Ap,” “App,” and “Appl” may be eliminated from concern when“car” and “Apple” are each associated with rules that identify maliciouscontent. As such, the storing of output states of a previously scanneddata block combined with correlating those output states with identifiedinput states that may be included in a subsequently received, previouslyordered data block may be referred to as a “reduction phase” consistentwith the present disclosure. Processing phases of the present disclosurerelated to the scanning of a data block may be referred to as a“scanning phase” of the present disclosure. Reduction phases andscanning phases may, thus, reduce memory utilization and increase theefficiency of a computer.

Finally after data block B 1-1 is received, data block B 1-1 may bescanned from an initial state (such as a null state) and output states1-1 may be output. The dotted line 320 indicates that output states 1-1may be compared with the identified input states when identifyingwhether the combined data blocks B 1-2 and B 2-1 include maliciouscontent. Note that this process scans data blocks received out of orderfor malicious content without reassembling the data blocks. Instead aseries of identified input states may be used when scanning an out oforder packet for malicious content. The presently disclosed invention,thus, identifies malicious content by comparing output states withidentified input states that may be included in a data block that hasnot yet been received. Later when the out of order data block isreceived, the out of order data block may be scanned generating one ormore output states. When an output state of the out of order packetincludes an identified input state of a subsequently ordered data block,the two different data blocks may include malicious content.

In certain instances one or more output states associated with differentpieces of a data set may be stored in memory where each of these outputstates may be associated with a possible identified input stateassociated with yet other pieces of the data set. When one or moreoutput states and one or more possible identified input states arestored in memory and an outstanding piece of the data set is received,the outstanding piece of the data set may be scanned generating anoutput state associated with the outstanding piece of the data set. Insuch an instance, each of the output states and possible identifiedinput states may be assembled in a chain when identifying that the dataset includes malicious content.

For example, when data blocks are received in the order illustrated inFIG. 3 (i.e.: B 2-2, B 1-2, B 2-1, and B 1-1) where data block B 2-2consists of “pple,” data block B 1-2 consists of “aaaa,” B 2-1 consistsof “araA,” and data block B 1-1 consists of “Appc.” First data block B2-2 is scanned using the identified input states (i.e. all possibleinput states that correspond to malicious content) generating outputstates 2-2. Since data block B 2-2 consists of “pple,” output states 2-2may identify that the identified input state of “A” from the not yetreceived data block B 2-1 will indicate that malicious content of“Apple” spans data block B 2-1 and B 2-2 when data block B 2-1 ends withthe character “A.” Since data block B 2-1 has not yet been received,output states 2-2 will identify that the identified input state of “A”preceding data block B 2-2 corresponds to malicious content “Apple.”

Next data block B 1-2 is scanned using the identified input statesgenerating output states 1-2. When rules that identify malicious contentas being “car” and “Apple” the character sequences an empty string (i.e.an initial state), “c,” “ca”, “A,” “Ap,” “App,” and “Appl” each areidentified input states that are associated with malicious content.Since data block B 1-2 consists of “aaaa,” the only output state thatcorresponds to an identified input state that may be associated withmalicious content is the empty string (i.e. an initial state). This isbecause the character sequences of “a,” “aa,” “aaa,” and “aaaa” are notassociated with malicious content according to rules that identify“Apple” and “car” as being malicious content. This means that data blockB 2-1 may be scanned from just the empty string. Thus, in this example,the process of reduction identifies that the only identified input stateof all of the identified input states that data block B 2-1 should bescanned from is the empty string.

When data block B 2-1 is received, it is scanned from only the emptystring. After data block B 2-1 is scanned, output states 2-1 will begenerated. Since data block B 2-1 consists of “araA,” the only outputstate that corresponds to an identified input state is the identifiedoutput state of “A.” Since data block B 2-2 has already been scanned andidentified as including “pple,” malicious content of “Apple” will bedetected in the data set when preceding data block B 2-1 ends with thecharacter “A.” Since, in this example, the identified input state of “A”precedes data block B 2-2, the malicious content of “Apple” is detectedin the data set. Once malicious content has been detected in the dataset, the receipt of additional data blocks, such as data block B 1-1,may be blocked. Note also that a chain of only one possible identifiedinput state of “A” of data block B 2-2 and the output state “pple” ofoutput states 2-2 are used to identify malicious content in thisexample. Note also that only a reduced number of input states coupledwith a number of output states 2-2 requires limited storage as comparedto storing the data blocks received.

The present disclosure is not limited to malicious content spanning oneor two data blocks, as methods consistent with the present disclosuremay detect malicious content that spans any number of data blocks in adata set, including all of the data blocks.

FIG. 4 illustrates a state mapping that includes malicious content.Whether the mapping moves from one particular state to anotherparticular state depends on the sequence of characters in the data set.FIG. 4 illustrates a mapping that moves from an initial state of S0 tostate S1 when the character “A” is scanned in a data set. FIG. 4 alsoshows the mapping moving from state S0 to state S6 when the character“c” is scanned in the data set. When the state map is in state S0 andthe next character input is not an “A” or a “c”, the mapping will stayin state S0. FIG. 4 identifies two different rules that identifymalicious content. Here the first rule identifies that the charactersequence of “Apple” is associated with malicious content and the secondrule identifies that the character sequence “car” is associatedmalicious content.

FIG. 4 also illustrates the state mapping moving consistent with thepresent disclosure. FIG. 4 illustrates a state mapping moving from stateS1 to state S2 when a “p” is scanned after an “A,” moving from state S2to S3 when a second “p” is scanned, moving from state S3 to S4 when an“1” is scanned, and moving from state S4 to S5 when an “e” is scanned.Note that state S5 is identified as item 410. Item 410 indicates thatthe malicious content “Apple” has been identified according to the firstrule in the data set.

Similarly state flow may move from state S0 to state S6 when thecharacter “c” is in the data set, then moves to state S7 when asubsequent character “a” is encountered in sequence in the data set, andthen moves from state S7 to state S8 when a subsequent character “r” isin the data set. Note that state S8 is identified as item 420 in FIG. 4.Item 420 indicates that malicious content “car” has been detected in thedata set. Here again each character “c,” “a,” and “r” must be sequentialcharacters in the data set for the state mapping to reach state S8.Whenever a next character identified in the data set does not follow thestate mapping, the mapping will move from a current state to state S0.When the state mapping moves from state S6 or S7 to state S0 (asindicated by the dotted lines in FIG. 4), malicious content has not beendetected in the data set. After state S8 the state mapping moves back toinitial state S0.

Dashed lines in FIG. 4 illustrate the state mapping moving from each ofstates S1, S2, S3, S4, and S5 back to state S0. In order to reach stateS5 each of characters “A,” “p,” “p,” “1,” and “e” must occur in order inthe data set. When a character in the data set does not agree with thestate mapping, malicious content is not detected in the data set and thestate mapping moves back to state S0.

FIG. 5 is a block diagram of a device for implementing the presenttechnology. FIG. 5 illustrates an exemplary computing system 500 thatmay be used to implement a computing device for use with the presenttechnology. The computing system 500 of FIG. 5 includes one or moreprocessors 510 and memory 520. Main memory 520 may store, in part,instructions and data for execution by processor 510. Main memory canstore the executable code when in operation. The system 500 of FIG. 5further includes a storage 520, which may include mass storage andportable storage, antenna 540, output devices 550, user input devices560, a display system 570, and peripheral devices 580.

The components shown in FIG. 5 are depicted as being connected via asingle bus 590. However, the components may be connected through one ormore data transport means. For example, processor unit 510 and mainmemory 520 may be connected via a local microprocessor bus, and thestorage 530, peripheral device(s) 580 and display system 570 may beconnected via one or more input/output (I/O) buses.

Storage device 530, which may include mass storage implemented with amagnetic disk drive or an optical disk drive, may be a non-volatilestorage device for storing data and instructions for use by processorunit 510. Storage device 530 can store the system software forimplementing embodiments of the present invention for purposes ofloading that software into main memory 510.

Portable storage device of storage 530 operates in conjunction with aportable non-volatile storage medium, such as a floppy disk, compactdisk or Digital video disc, to input and output data and code to andfrom the computer system 500 of FIG. 5. The system software forimplementing embodiments of the present invention may be stored on sucha portable medium and input to the computer system 500 via the portablestorage device.

Antenna 540 may include one or more antennas for communicatingwirelessly with another device. Antenna 540 may be used, for example, tocommunicate wirelessly via Wi-Fi, Bluetooth, with a cellular network, orwith other wireless protocols and systems. The one or more antennas maybe controlled by a processor 510, which may include a controller, totransmit and receive wireless signals. For example, processor 510execute programs stored in memory 520 to control antenna 540 transmit awireless signal to a cellular network and receive a wireless signal froma cellular network.

The system 500 as shown in FIG. 5 includes output devices 550 and inputdevice 560. Examples of suitable output devices include speakers,printers, network interfaces, and monitors. Input devices 560 mayinclude a touch screen, microphone, accelerometers, a camera, and otherdevice. Input devices 560 may include an alpha-numeric keypad, such as akeyboard, for inputting alpha-numeric and other information, or apointing device, such as a mouse, a trackball, stylus, or cursordirection keys.

Display system 570 may include a liquid crystal display (LCD), LEDdisplay, or other suitable display device. Display system 570 receivestextual and graphical information, and processes the information foroutput to the display device.

Peripherals 580 may include any type of computer support device to addadditional functionality to the computer system. For example, peripheraldevice(s) 580 may include a modem or a router.

The components contained in the computer system 500 of FIG. 5 are thosetypically found in computing system, such as but not limited to a desktop computer, lap top computer, notebook computer, net book computer,tablet computer, smart phone, personal data assistant (PDA), or othercomputer that may be suitable for use with embodiments of the presentinvention and are intended to represent a broad category of suchcomputer components that are well known in the art. Thus, the computersystem 500 of FIG. 5 can be a personal computer, hand held computingdevice, telephone, mobile computing device, workstation, server,minicomputer, mainframe computer, or any other computing device. Thecomputer can also include different bus configurations, networkedplatforms, multi-processor platforms, etc. Various operating systems canbe used including Unix, Linux, Windows, Macintosh OS, Palm OS, and othersuitable operating systems.

Actions taken when the content included in a data set or file receivedat an application level at a peer device may vary and may depend on oneor more actions identified by a user of the peer computer. In certaininstances, user preferred actions may be selected in a user interfacedisplayed on a display at the peer computer. In other instances actionstaken after detecting malicious content may be according to a set ofpre-defined or default actions set in an application program. Actionsthat may be taken after detecting malicious content in a data setinclude, yet are not limited to marking the data set or file asincluding malicious content, blocking reception of data associated withthe data set or file, and resetting one or more TCP connectionsassociated with the data set or file.

When the data set or file is marked as including malicious content, thatmarking may be stored in a table or database at the peer computer thatreceived and detected the malicious data. The data set or file may beidentified by a name (i.e. by a filename) or may be identified using aHash function or checksum of information that identifies the data set.Once a data file has been identified subsequent attempts to download thefile may be blocked.

Hash functions identifying a data set or file may be generated frommetadata downloaded from a peer when downloading a portion of a dataset. In certain instances the downloaded metadata may include a peeridentifier, an internet protocol (IP) address, a domain name, or a portnumber.

As soon as a file is identified as being associated with maliciouscontent, one or more communication sessions associated with the file maybe reset. This may include resetting communications sessions between aplurality of peer computers that are providing parts of the file.

The presently disclosure is not limited to files received over a peer topeer network as file data received in an interleaved (out of order)sequence at the application level may also be scanned according to thepresent disclosure. For example, interleaved data received using theserver message block (SMB) 2.0 standard may be scanned in order withoutreassembly at the application layer of a computer for malicious content.

Embodiments of the present disclosure may be implemented by anon-transitory computer readable storage medium by a processor executinginstructions out of a memory, by a DPI scanner implemented in a fieldprogrammable gate array (FPGA).

The presently disclosed invention may be implemented in software (i.e.as a non-transitory computer readable storage medium executable by aprocessor), may be implemented in whole or in part in a fieldprogrammable gate array, may be implemented in whole or in part in ahardware state machine, or may be implemented in a combination ofhardware and software.

The various methods may be performed by software operating inconjunction with hardware. For example, instructions executed by aprocessor, the instructions otherwise stored in a non-transitorycomputer readable medium such as memory. Various interfaces may beimplemented—both communications and interface. One skilled in the artwill appreciate the various requisite components of a mobile device andintegration of the same with one or more of the foregoing figures and/ordescriptions.

The foregoing detailed description of the technology has been presentedfor purposes of illustration and description. It is not intended to beexhaustive or to limit the technology to the precise form disclosed.Many modifications and variations are possible in light of the aboveteaching. The described embodiments were chosen in order to best explainthe principles of the technology, its practical application, and toenable others skilled in the art to utilize the technology in variousembodiments and with various modifications as are suited to theparticular use contemplated. It is intended that the scope of thetechnology be defined by the claim.

What is claimed is:
 1. A method for deep packet inspection scanning, themethod comprising: receiving a first portion of a data set at anapplication layer of a computer system in an out of order sequence;identifying a first input state associated with the data set, whereinthe first input state includes a portion of information included in apiece of malicious content identified by a rule; scanning with the DPIscanner the first portion of the received data set at the applicationlayer from at least the first input state; generating a first outputstate based on the scan of the first portion, wherein the first outputstate corresponds to the malicious content; identifying that a secondportion of the data set follows the first portion of the data set;scanning with the DPI scanner the second portion of the data set fromthe first output state; generating a second output state based on thescan of the second portion; identifying that a third portion of the dataset precedes the first portion of the data set; scanning the thirdportion of the data set from the first input state; generating a thirdoutput state based on the scan of the third portion; identifying thatthe third output state corresponds to the first input state; andindicating that the data set contains the malicious content, wherein thefirst input state, the first output state, and the second output statecorresponds to the rule.
 2. The method of claim 1, further comprisingterminating the reception of the data set after identifying that thereceived data set includes malicious content.
 3. The method of claim 1,wherein information identifying that the data set includes maliciouscontent is stored in a database.
 4. The method of claim 3, furthercomprising: receiving a subsequent request to download the data set;identifying that the data set is associated with malicious content; andblocking the subsequent request to download the data set.
 5. The methodof claim 1, wherein a first portion of the at least portion of the dataset is received from a first peer computer of a peer to peer network,and a second portion of the at least portion of the data set is receivedfrom a second peer computer in the peer to peer network.
 6. Anon-transitory computer-readable storage medium having embodied thereona program executable by a processor to perform a method for deep packetinspection scanning, the method comprising: receiving a first portion ofa data set at an application layer of a computer system in an out oforder sequence; identifying a first input state associated with the dataset, wherein the first input state includes a portion of informationincluded in a piece of malicious content identified by a rule; scanningwith the DPI scanner the first portion of the received data set at theapplication layer from at least the first input state; generating afirst output state based on the scan of the first portion, wherein thefirst output state corresponds to the malicious content; identifyingthat a second portion of the data set follows the first portion of thedata set; scanning with the DPI scanner the second portion of the dataset from the first output state; generating a second output state basedon the scan of the second portion; identifying that a third portion ofthe data set precedes the first portion of the data set; scanning thethird portion of the data set from the first input state; generating athird output state based on the scan of the third portion; identifyingthat the third output state corresponds to the first input state; andindicating that the data set contains the malicious content, wherein thefirst input state, the first output state, and the second output statecorresponds to the rule.
 7. The non-transitory computer readable-storagemedium of claim 6, wherein the program further comprises instructionsexecutable to terminate the reception of the data set after identifyingthat the received data set includes malicious content.
 8. Thenon-transitory computer-readable storage medium of claim 6, whereininformation identifying that the data set includes malicious content isstored in a database.
 9. The non-transitory computer-readable storagemedium of claim 8, wherein the program further comprises instructionsexecutable to: receive a subsequent request to download the data set;identify that the data set is associated with malicious content; andblock the subsequent request to download the data set.
 10. Thenon-transitory computer-readable storage medium of claim 6, wherein afirst portion of the at least portion of the data set is received from afirst peer computer of a peer to peer network, and a second portion ofthe at least portion of the data set is received from a second peercomputer in the peer to peer network.
 11. An apparatus for performingdeep packet inspection scanning, the apparatus comprising: a networkinterface that receives a first portion of a data set at an applicationlayer of a computer system in an out of order sequence; and a processorthat executes instructions stored in memory, wherein execution of theinstructions by the processor: identifies a first input state associatedwith the data set, wherein the first input state includes a portion ofinformation included in a piece of malicious content identified by arule; scans the first portion of the received data set at theapplication layer from the first input state; generates a first outputstate based on the scan of the first portion, wherein the first outputstate corresponds to the malicious content; identifies a second portionof the data set follows the first portion of the data set; identifiesthat the first output state that corresponds to a rule describingmalicious content; scans with the DPI scanner the second portion of thedata set from the first output state; generates a second output statebased on the scan of the second portion; identifies that a third portionof the data set precedes the first portion of the data set; scans the atleast third portion of the data set from the first input state;generates a third output state based on the scan of the third portion;identifying that the third output state corresponds to the first inputstate; and indicates that the data set contains the malicious content,wherein the first input state, the first output state, and the secondoutput state corresponds to the rule.
 12. The apparatus of claim 11,wherein the processor terminates the reception of the data set afteridentifying that the received data set includes malicious content. 13.The apparatus of claim 11, wherein information identifying that the dataset includes malicious content is stored in a database.
 14. Theapparatus of claim 13, wherein the network interface receives asubsequent request to download the data set; and wherein the processor:identifies that the data set is associated with malicious content; andblocks the subsequent request to download the data set.
 15. Theapparatus claim 11, wherein a first portion of the at least portion ofthe data set is received from a first peer computer of a peer to peernetwork, and a second portion of the at least portion of the data set isreceived from a second peer computer in the peer to peer network.